1. Field of the Invention
The present invention relates to a printed circuit board. More particularly, the present invention relates to a mechanical-laser structure on a printed circuit board and a carrier.
2. Description of the Related Art
A trend for electrical products is to be light, short, small and thin. Not only the design of a circuit on a substrate but also the manufacturing technology of the substrate should be improved to meet these trends. A linewidth of the circuit is more narrowly formed to increase the layout density. Additionally, a diameter of a through hole is also narrower to speed up the operation of the circuit.
The through hole is mostly formed by mechanical drilling in the current. The narrowest diameter of the through hole formed by mechanical drilling is 0.2 mm. This the limitation of the machine, so is hard to reduce the diameter of the through hole more. The area occupied by the through hole is large. Furthermore, it is also more difficult to reduce the routing density, so RC delay is large. Laser drilling is another method of forming the through hole, and the diameter of the through hole formed by laser drilling is narrower than 0.2 mm, which means that laser drilling overcomes drawbacks of mechanical drilling. However, the substrate usually contains glass fiber layers which decrease the efficiency of laser drilling. As a result, the manufacturing cost and the manufacturing time are increased.
Accordingly, the present invention provides a mechanical-laser structure on a printed circuit board and a carrier in which the routing density and RC delay are reduced.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a method for fabricating a mechanical-laser structure on a printed circuit board and a carrier. The method includes the following steps. A substrate is provided. A first through hole is formed in the substrate by mechanical drilling. An epoxy plug is formed within the first through hole. A conductive layer is formed on the substrate by compression. The conductive layer is patterned to form conducting wires and exposes the epoxy plug. A micro via is formed within the epoxy plug by laser drilling.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides a mechanical-laser structure. A substrate having a first through hole is provided. A plug is formed within the first through hole. A second through hole is formed in the plug.
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides another mechanical-laser structure, A central layer having a first through hole is provided. A first conducting wire is formed on the central layer, and the first through hole is exposed. A first conductive layer is formed on a sidewall of the first through hole and coupled with the first conducting wire. An insulation layer is formed on the first conducting wire and fills the first through hole to form a plug. A second through hole is formed in the plug. A second conducting wire is formed on the insulation layer, and the second through hole is exposed. A second conductive layer is formed on a sidewall of the second through hole and coupled with the second conducting wire.
By using epoxy, the efficiency of laser drilling is improved. As a result, the manufacturing time and the manufacturing cost are decreased. Since the micro via is formed by laser drilling, the diameter of the micro via is narrower. The layout density is increased. Furthermore, the routing density and RC delay are reduced.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention a s claimed.